Though they may sound like the product of a moment of stoner culinary genius, karepan (curry-filled doughnuts), are a legitimate and widespread snack in Japan.

Though they may sound like the product of a moment of stoner culinary genius, karepan (curry-filled doughnuts) are a legitimate and widespread snack in Japan. They have a history dating back more than 100 years, an official association to further their cause (The Japanese Currypan Association), and even an eponymous anime character, Karepanman, created by renowned anime artist Takashi Yanase (of Anpanman fame), and armed with the superpower of squirting curry sauce from his head.

There are a range of species within the currypan genus, but the key features are a soft, slightly sweet, miniature rugby-ball shaped doughnut bun, a filling of Japanese curry, and a crunchy coating. Oh, and they're typically deep-fried.This holy trinity of meat, carbs, and oil can be found throughout Japan, everywhere from combinis (convenience stores), to supermarkets, standard bakery chains like Little Mermaid and Delifrance, upmarket foreign import bakeries like Joel Robuchon and Gontran Cherrier, currypan festivals, and dedicated currypan specialty stores.

Toyofuku, located in Tokyo's Asakusa district, is one such specialty store. Tencho Nori Masayuki serves up his signature currypan using curry made with premium Japanese kurogewagyu beef. Kurogewagyu is the product of Japanese black-haired wagyu cattle that have been raised in relaxed environments, surrounded by bountiful nature, fed selective grasses and plants not treated with chemicals, given access to fresh spring water, received massages, and taken a little beer with their meals. It's this level of luxe that gives the meat its prized rich, sweet, aromatic, luxuriously fatty, and smooth characteristics. During his time running a bar in Nishi-Azabu, Masayuki became acquainted with the widespread love for Japanese curry, and decided to undertake a refining of the curry proposition using wagyu beef and showcasing it in a currypan.

While it may not sound particularly Japanese, the curry concept has been thriving in Japan since the 1850s. It arrived via Anglo-Indian officers of the British Royal Navy, who came to Japan once the Edo-era isolationist ban on foreign interaction ended. Japanese curry, with its fairly amorphous-tasting mix of spices, gravy-like consistency, sweet flavor, and packet-mix accessibility, achieved wide appeal. These days, curry is one of the most commonly eaten foods in Japan, particularly with sticky Japanese rice (kare-raisu) and udon (kare-udon).

Encasing spoonfuls of curry is the pan, a term similar to the French term for bread that in Japan encompasses a full spectrum of bread and dough-related products. Yakisobapan is a hot dog bun filled with yakisoba. Anpan is a sweet bun filled with anko (sweet red bean paste). Mentaiko Furansu Pan is a French baguette filled with mentaiko (cod roe) and cheese. Doughnut-style dough is typically used for currypan, which provides a soft, sweet and pleasantly yeasty enclosure for the curry. It crisps up nicely on frying (or baking, but usually frying) while remaining soft on the interior. Experimental deviations—like charcoal muffin-like casings, shokupan curry toastie-like casings, or lazy bread roll casings—may be encountered, but are less common.

The currypan's finishing touch is a solid coating of panko, a type of Japanese breadcrumb typically made using crustless toasted white bread, with the bread processed into flakes rather than ground into crumbs. This flake-like structure has a light, airy texture that absorbs less oil than crumbs, and crisps up perfectly when deep-fried.

Toyofuku currypan shop is on a food vendor street by the busy tourist hotspot of Asakusa temple, nestled between stores selling menchi katsu (crumbed and fried mince patties) and ice-cream filled monaka (traditional wafers). Surrounding Toyofuku is a mixed crowd of locals, tourists, kids and kimonoed young women in the midst of currypan selfies and exclaims of oishi-sou ("looks delicious!") and umai ("delicious!"). There are two flavors on offer—regular and spicy (karakuchi). During warmer months days, Masayuki tells me he moves 400 units of the golden nuggets. In winter, when the call of steaming curry-filled bun runs strong, sales go up to 700.

When I visit, the wagyu is an A4-grade Ohmi cut from the Shiga prefecture. Other days, it may be wagyu from Kobe, Miyagi, Kagoshima, or Hokkaido. Toyofuku's curry is a deep, sexy, dark brown shade of gravy and is filled with tender beef chunks. In addition to the characteristic Japanese curry spice mix, Masayuki tells me it's "aka-wine-poi"—heavily red wine flavoured, with a cooking time of no less than eight hours. The result is a rich, smooth curry.

Masayuki fries his currypan in cottonseed oil, which allows for a higher smoke point and produces a kara texture (hard and crispy), while retaining a soft and fluffy (fuwa fuwa) interior. The even larger than standard panko crumbs, with their generous surface area, make for a crisp mouthfeel (saku saku) that makes the sound product development teams chase for years. Expect a face full of oozing curry when you bite through the doughnut shell, as Nori-san doesn't skimp on the filling.

Wagyu curry doughnuts—get them while they're hot. And by the way, they're just ¥260 a piece.